/*
** $Id: lfunc.c $
** Auxiliary functions to manipulate prototypes and closures
** See Copyright Notice in lua.h
*/

#define lfunc_c
#define LUA_CORE

#include "lprefix.h"

#include <stddef.h>

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"

CClosure *luaF_newCclosure(lua_State *L, int nupvals)
{
    GCObject *o = luaC_newobj(L, LUA_VCCL, sizeCclosure(nupvals));
    CClosure *c = gco2ccl(o);
    c->nupvalues = cast_byte(nupvals);
    return c;
}

LClosure *luaF_newLclosure(lua_State *L, int nupvals)
{
    GCObject *o = luaC_newobj(L, LUA_VLCL, sizeLclosure(nupvals));
    LClosure *c = gco2lcl(o);
    c->p = NULL;
    c->nupvalues = cast_byte(nupvals);
    while (nupvals--)
        c->upvals[nupvals] = NULL;
    return c;
}

/*
** fill a closure with new closed upvalues
*/
void luaF_initupvals(lua_State *L, LClosure *cl)
{
    int i;
    for (i = 0; i < cl->nupvalues; i++) {
        GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));
        UpVal *uv = gco2upv(o);
        uv->v = &uv->u.value; /* make it closed */
        setnilvalue(uv->v);
        cl->upvals[i] = uv;
        luaC_objbarrier(L, cl, uv);
    }
}

/*
** Create a new upvalue at the given level, and link it to the list of
** open upvalues of 'L' after entry 'prev'.
**/
static UpVal *newupval(lua_State *L, int tbc, StkId level, UpVal **prev)
{
    GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));
    UpVal *uv = gco2upv(o);
    UpVal *next = *prev;
    uv->v = s2v(level); /* current value lives in the stack */
    uv->tbc = tbc;
    uv->u.open.next = next; /* link it to list of open upvalues */
    uv->u.open.previous = prev;
    if (next)
        next->u.open.previous = &uv->u.open.next;
    *prev = uv;
    if (!isintwups(L)) {        /* thread not in list of threads with upvalues? */
        L->twups = G(L)->twups; /* link it to the list */
        G(L)->twups = L;
    }
    return uv;
}

/*
** Find and reuse, or create if it does not exist, an upvalue
** at the given level.
*/
UpVal *luaF_findupval(lua_State *L, StkId level)
{
    UpVal **pp = &L->openupval;
    UpVal *p;
    lua_assert(isintwups(L) || L->openupval == NULL);
    while ((p = *pp) != NULL && uplevel(p) >= level) { /* search for it */
        lua_assert(!isdead(G(L), p));
        if (uplevel(p) == level) /* corresponding upvalue? */
            return p;            /* return it */
        pp = &p->u.open.next;
    }
    /* not found: create a new upvalue after 'pp' */
    return newupval(L, 0, level, pp);
}

/*
** Call closing method for object 'obj' with error message 'err'. The
** boolean 'yy' controls whether the call is yieldable.
** (This function assumes EXTRA_STACK.)
*/
static void callclosemethod(lua_State *L, TValue *obj, TValue *err, int yy)
{
    StkId top = L->top;
    const TValue *tm = luaT_gettmbyobj(L, obj, TM_CLOSE);
    setobj2s(L, top, tm);      /* will call metamethod... */
    setobj2s(L, top + 1, obj); /* with 'self' as the 1st argument */
    setobj2s(L, top + 2, err); /* and error msg. as 2nd argument */
    L->top = top + 3;          /* add function and arguments */
    if (yy)
        luaD_call(L, top, 0);
    else
        luaD_callnoyield(L, top, 0);
}

/*
** Check whether object at given level has a close metamethod and raise
** an error if not.
*/
static void checkclosemth(lua_State *L, StkId level)
{
    const TValue *tm = luaT_gettmbyobj(L, s2v(level), TM_CLOSE);
    if (ttisnil(tm)) {                           /* no metamethod? */
        int idx = cast_int(level - L->ci->func); /* variable index */
        const char *vname = luaG_findlocal(L, L->ci, idx, NULL);
        if (vname == NULL)
            vname = "?";
        luaG_runerror(L, "variable '%s' got a non-closable value", vname);
    }
}

/*
** Prepare and call a closing method.
** If status is CLOSEKTOP, the call to the closing method will be pushed
** at the top of the stack. Otherwise, values can be pushed right after
** the 'level' of the upvalue being closed, as everything after that
** won't be used again.
*/
static void prepcallclosemth(lua_State *L, StkId level, int status, int yy)
{
    TValue *uv = s2v(level); /* value being closed */
    TValue *errobj;
    if (status == CLOSEKTOP)
        errobj = &G(L)->nilvalue;               /* error object is nil */
    else {                                      /* 'luaD_seterrorobj' will set top to level + 2 */
        errobj = s2v(level + 1);                /* error object goes after 'uv' */
        luaD_seterrorobj(L, status, level + 1); /* set error object */
    }
    callclosemethod(L, uv, errobj, yy);
}

/*
** Maximum value for deltas in 'tbclist', dependent on the type
** of delta. (This macro assumes that an 'L' is in scope where it
** is used.)
*/
#define MAXDELTA \
    ((256ul << ((sizeof(L->stack->tbclist.delta) - 1) * 8)) - 1)

/*
** Insert a variable in the list of to-be-closed variables.
*/
void luaF_newtbcupval(lua_State *L, StkId level)
{
    lua_assert(level > L->tbclist);
    if (l_isfalse(s2v(level)))
        return;              /* false doesn't need to be closed */
    checkclosemth(L, level); /* value must have a close method */
    while (cast_uint(level - L->tbclist) > MAXDELTA) {
        L->tbclist += MAXDELTA; /* create a dummy node at maximum delta */
        L->tbclist->tbclist.delta = 0;
    }
    level->tbclist.delta = cast(unsigned short, level - L->tbclist);
    L->tbclist = level;
}

void luaF_unlinkupval(UpVal *uv)
{
    lua_assert(upisopen(uv));
    *uv->u.open.previous = uv->u.open.next;
    if (uv->u.open.next)
        uv->u.open.next->u.open.previous = uv->u.open.previous;
}

/*
** Close all upvalues up to the given stack level.
*/
void luaF_closeupval(lua_State *L, StkId level)
{
    UpVal *uv;
    StkId upl; /* stack index pointed by 'uv' */
    while ((uv = L->openupval) != NULL && (upl = uplevel(uv)) >= level) {
        TValue *slot = &uv->u.value; /* new position for value */
        lua_assert(uplevel(uv) < L->top);
        luaF_unlinkupval(uv);   /* remove upvalue from 'openupval' list */
        setobj(L, slot, uv->v); /* move value to upvalue slot */
        uv->v = slot;           /* now current value lives here */
        if (!iswhite(uv)) {     /* neither white nor dead? */
            nw2black(uv);       /* closed upvalues cannot be gray */
            luaC_barrier(L, uv, slot);
        }
    }
}

/*
** Remove firt element from the tbclist plus its dummy nodes.
*/
static void poptbclist(lua_State *L)
{
    StkId tbc = L->tbclist;
    lua_assert(tbc->tbclist.delta > 0); /* first element cannot be dummy */
    tbc -= tbc->tbclist.delta;
    while (tbc > L->stack && tbc->tbclist.delta == 0)
        tbc -= MAXDELTA; /* remove dummy nodes */
    L->tbclist = tbc;
}

/*
** Close all upvalues and to-be-closed variables up to the given stack
** level.
*/
void luaF_close(lua_State *L, StkId level, int status, int yy)
{
    ptrdiff_t levelrel = savestack(L, level);
    luaF_closeupval(L, level);                /* first, close the upvalues */
    while (L->tbclist >= level) {             /* traverse tbc's down to that level */
        StkId tbc = L->tbclist;               /* get variable index */
        poptbclist(L);                        /* remove it from list */
        prepcallclosemth(L, tbc, status, yy); /* close variable */
        level = restorestack(L, levelrel);
    }
}

Proto *luaF_newproto(lua_State *L)
{
    GCObject *o = luaC_newobj(L, LUA_VPROTO, sizeof(Proto));
    Proto *f = gco2p(o);
    f->k = NULL;
    f->sizek = 0;
    f->p = NULL;
    f->sizep = 0;
    f->code = NULL;
    f->sizecode = 0;
    f->lineinfo = NULL;
    f->sizelineinfo = 0;
    f->abslineinfo = NULL;
    f->sizeabslineinfo = 0;
    f->upvalues = NULL;
    f->sizeupvalues = 0;
    f->numparams = 0;
    f->is_vararg = 0;
    f->maxstacksize = 0;
    f->locvars = NULL;
    f->sizelocvars = 0;
    f->linedefined = 0;
    f->lastlinedefined = 0;
    f->source = NULL;
    return f;
}

void luaF_freeproto(lua_State *L, Proto *f)
{
    luaM_freearray(L, f->code, f->sizecode);
    luaM_freearray(L, f->p, f->sizep);
    luaM_freearray(L, f->k, f->sizek);
    luaM_freearray(L, f->lineinfo, f->sizelineinfo);
    luaM_freearray(L, f->abslineinfo, f->sizeabslineinfo);
    luaM_freearray(L, f->locvars, f->sizelocvars);
    luaM_freearray(L, f->upvalues, f->sizeupvalues);
    luaM_free(L, f);
}

/*
** Look for n-th local variable at line 'line' in function 'func'.
** Returns NULL if not found.
*/
const char *luaF_getlocalname(const Proto *f, int local_number, int pc)
{
    int i;
    for (i = 0; i < f->sizelocvars && f->locvars[i].startpc <= pc; i++) {
        if (pc < f->locvars[i].endpc) { /* is variable active? */
            local_number--;
            if (local_number == 0)
                return getstr(f->locvars[i].varname);
        }
    }
    return NULL; /* not found */
}
